Case-hardening mixture.



UNITED STATES PATENT OFFICE.

JAMFiSF. SALLOWS, OELANSING. MICHIGAN. ASSIGNOR T0 ALFRED O. BLAICH, OF

CHICAGO.

ILLINOIS;

CASEEHARDENING MIXTURE.

No Drawing.

To all whom it may concern:

lie it known that I, Jam-s l. b..\i.i.ows, a citizen of the United States, residing: at Lansing, in the county of Ingham and State of Michigan, have invented certain new and useful Improvements in Case-Hardening Mixtures, of which the following is a specification.

This invention relates to material for use in cementing or case-hardening.

Most mixtures employed for the purpose of cementation or case-hardening by dry packing comprise as the essential element from which the carbon isto be derived, some comparatively costly substance, such as bonedust or powdered charred leather charcoal. I have discovered, however, that the spent tan bark commonly known as tan waste,-

ing substances commonly employed, which.

are salts of alkaline bases such as sodium carbonate, barium carbonate and ammonium carbonates, slaked lime being preferably added with some of these salts and pennies-'- sible with any of them.

A very effective mixture for the purpose, consists of from 65. to 7 0 per cent.1of thetan waste above mentioned, preferably powdered "and intimately mixed'withfrom'lito 15 percent. of barium carbonate, about 5 per cent. of soda ash, from 8 to 10 per cent. of

slaked lime and about 2% per cent. of ammonium carbonate. If it is preferred to avoid-the unpleasantness of the use of so-.

dium carbonate, I find that about 10 per cent. of common saltmay be substituted for this element of the combination. When properly mixed and used in the ordinary manner, that is, by embedding the article to be'case-hardened in the mixture'and heating to incandescence, the resulting surface will. contain as high as 1.35, per cent. carbon as Specification of Letters Patent.

Application filed December 26. 1912. Serial No. 738.703.

Patented Dec. 2. 1913.

on account of the absence of other uses for the tan waste which is the principal ingredicntof the mixture. this material is both cheap and abundant.

When any of the sodium salts mentioned is employed, the use therewith of the slaked lime has the effect of retaining the chemical elements which would otherwise pass ofl' in rapor so'that theyinay produce their desired effect in ccmbinationwith the carbonaceous matter.

The tan waste can be used either charred or not charred. The advantage of charring is reduction of volume so that there is less shrinkage of the mixture in use. There is always more or less fine dustwith the tan waste and this is especially true when it is charred, and on this account I prefer to spray it'with' oil,-hydro-carbon oil being -pref erred, before mixing it with the elements. The amount of oil used should be only such as to lay the dust without making the mixture wet. i

A case-hardenin mixture Iconsisting -principally of tanbar I combinediin physi cal mixture with energizin material comprisingsalts'o'f an alkaline ase for rendermg-the carbonaceous matter of the tan bark 3 active when the mixture is heated.

. 21A" case hardening mixture consisting principally of carbonaceous material in tl-e form of spent tan bark combined in physical mixture with ,energizin material comprising a sodium salt and sh: the carbonaceous matter-active. when the mixture is heated,.-

3. A case-hardening mixture consisting principally of, carbonaceous material in the form of spent-tan bark mixed with energizing substance, including barium carbonate, a. sodium salt. sla'kedlime and ammonium carbonate.

4. A case-hardening mixture consisting:- of from 65 to 70 per cent. s ent tan 'bark,,12 to .15 per cent. barium car na-te,, 5 to 10 per cent. of a sodium salt, 8 to'lO per cent, slaked lime, and about 2% per cent. ammonium carbonate.

ked lime to render 5. A case-hardening mixture consisting of from 65 to 70 per cent. spent tan bark, 12 to i15per cent. barium carbonate, approximately x 10, per cent. sodium 'chlorid, 8 to 10 per cent.

1.5. slakedlime, and about 2%. per cent. annno- Ilium-carbonate.

x I i testimony wheregf I have hereunto set JAMES F. SALLOWS.

Witnesses CHAS. \V. F os'ren,

NETT'IE Kt-LL. 

